Wonderful news for Shropshire - but why wait until 2016 - stock cascade - IEP - Voyager with an electric coach?
Im not sure what sort of timeline the second half of your post is attempting to suggest, but if you were to attempt to tie in West Coast fleet changes with developments in the IEP programme then you would have an even longer wait than December 2016, as the first IEP trains are not due to begin entering service until mid-2017.
I would raise the fact that the Section 54 Agreement ensuring that the 221s are used within the West Coast franchise runs until December 2016, but given that it seems that all the 221s are to be retained within the West Coast franchise beyond 2016 then this seems to be irrelevant.
A four year procurement process from the earliest possible date of launching an initial invitation to tender for new rolling stock until delivery and entry into service of the new trains does not sound unreasonable compared to other recent rolling stock orders, so I would suggest that December 2016 is a sensible target date to have the new trains in service before additional destinations can be added to the West Coast network.
Finally, it may not be possible to Bi-mode Virgins 221s, as
Pumbaa has detailed in a different thread:
It has not proved possible to extend the concept to the 221s for two reasons;
a) the transformer car is to be unpowered; you can't fit powered bogies beneath, and cross feed them from ajoining cars without serious re-engineering and a complete lack of space besides. One transformer car can just about cope with the 4 cars. As soon as you add an extra car, the transformer car can't cope. So you either extend the 220s by 1 car to 5 cars, or by several cars to 8+. The economics just fall over at current.
b) assuming that the transformer capacity wasn't an issue, and you wanted to lengthen the 221s to 6-car or 5-car, you can't anyway. There is not enough space to fit the electro gubbins beneath the transformer car, fit tilting bogies, tilt controls and associated guff. It's just not feasible - there is simply not enough room underneath.
So that's the compromise. All 220s become 5 car and the 1 4-car 221 XC have. Virgin and the remaining 221s get diddly.